Critical shoulder angle combined with age predict five shoulder pathologies: a retrospective analysis of 1000 cases

Abstract

BackgroundAcromial morphology has previously been defined as a risk factor for some shoulder pathologies. Yet, study results are inconclusive and not all major shoulder diseases have been sufficiently investigated. Thus, the aim of the present study was to analyze predictive value of three radiological parameters including the critical shoulder angle, acromion index, and lateral acromion angle in relationship to symptomatic patients with either cuff tear arthropathy, glenohumeral osteoarthritis, rotator cuff tear, impingement, and tendinitis calcarea.MethodsA total of 1000 patients’ standardized true-anteroposterior radiographs were retrospectively assessed. Receiver-operating curve analyses and multinomial logistic regression were used to examine the association between shoulder pathologies and acromion morphology. The prediction model was derived from a development cohort and applied to a validation cohort. Prediction model’s performance was statistically evaluated.ResultsThe majority of radiological measurements were significantly different between shoulder pathologies, but the critical shoulder angle was an overall better parameter to predict and distinguish between the different pathologies than the acromion index or lateral acromion angle. Typical critical shoulder angle-age patterns for the different shoulder pathologies could be detected. Patients diagnosed with rotator cuff tears had the highest, whereas patients with osteoarthritis had the lowest critical shoulder angle. The youngest patients were in the tendinitis calcarea and the oldest in the cuff tear arthropathy group.ConclusionsThe present study showed that critical shoulder angle and age, two easily assessable variables, adequately predict different shoulder pathologies in patients with shoulder complaints.

Critical shoulder angle: Acromial coverage is more relevant than glenoid inclination

“…There is a great interest to change the radiological CSA towards to “normal” values and thereby reducing an overload of the rotator cuff. Although it has not yet been clarified which sub‐component (glenoid inclination, lateral acromial roof extension, acromial height) has the greatest impact, arthroscopic lateral acromioplasty is already performed . Our data could support lateral acromioplasty.…”

Critical shoulder angle is an effective radiographic parameter that is associated with rotator cuff tears and osteoarthritis: a systematic review

“…In contrast, smaller CSAs produce a resulting vector force of the deltoid that is unbalanced against the glenoid and thus, increasing the risk for the development of concentric osteoarthritis 8 29. Though our findings suggest that the CSA can be associated with other pathologies such as impingement27 and is not associated with glenoid erosion after hemiarthroplasty,36 further research is warranted to ascertain these results and to determine the mechanism through which they develop.…”

“…Three studies (n=323) found that those with osteoarthritis had a significantly lower CSA (p<0.05) 14 28 29. One study (n=500) reported a trend towards significance (OR=0.87 (95% CI 0.75 to 1.01); p=0.06) for the same association 27. One study (n=298) determined that of the patients with a CSA <30°, 93% had osteoarthritis 8.…”

“…Moreover, high agreement was sustained across various groups of patients with pathologies such as rotator cuff tears,8 10 14 15 22–24 26–33 35 osteoarthritis,8 10 14 15 27–29 35 repaired rotator cuffs,12 20 21 34 shoulder arthroplasty,36 37 adhesive capsulitis,22 cuff tear arthropathy,27 impingement,27 tendinitis calcarea,27 those without rotator cuff tears in need of either subacromial or GH injections,19 and instability 15. Included studies in this review also determined a high inter-rater agreement between a shoulder and elbow specialist in practice for 10 years and a graduate medical student,29 radiologists and orthopaedic surgeons14 15 19 and between orthopaedic surgeons themselves 8 21 22 28 30 31 35–37.…”

“…001) 27. Lastly, one study (n=58) examining the relationship between the CSA and symptomatic glenoid erosion after shoulder hemiarthroplasty, found no significant difference (p>0.05) in CSA measurements between the study (ie, symptomatic glenoid erosion after anatomic hemiarthroplasty) and control (ie, no signs of symptomatic glenoid erosion) groups regardless of arm position (ie, neutral, external or internal rotations) during measurement36 (online supplementary appendix table 2).…”